1. Field of the Invention
The present invention relates to a multilayer-film reflective mirror, an exposure apparatus, a device manufacturing method, and a manufacturing method of a multilayer-film reflective mirror.
2. Description of Related Art
In an exposure apparatus for use in a photolithography process, there is proposed an EUV exposure apparatus as disclosed for example in U.S. Patent Application, Publication No. 2005/0157384, in which Extreme Ultra-Violet (EUV) light is used as exposure light. In an optical system of an EUV exposure apparatus, a multilayer-film reflective mirror is used.
When a surface of a multilayer film of a multilayer-film reflective mirror is machined to remove a part of a layer of the surface in order to adjust an optical characteristic of the multilayer-film reflective mirror, there is a possibility of increasing the machining workload. Furthermore, when a surface of a multilayer film is machined to remove a part of a layer of the surface thereof, there is a possibility that a desired optical characteristic is not obtained due to a stepwise change in phase change amount between a machined region and an unmachined region, or the like.
A purpose of some aspects of the present invention is to provide a multilayer-film reflective mirror which can offer a desired optical characteristic. Another purpose is to provide a manufacturing method of a multilayer-film reflective mirror which can suppress increase in machining workload and offer a desired optical characteristic. Still another purpose is to provide an exposure apparatus capable of favorably exposing a substrate by use of a multilayer-film reflective mirror which offers a desired optical characteristic, and to provide a device manufacturing method using the exposure apparatus.